The former world No.1 has been receiving treatment for Sjögren's syndrome (an autoimmune disease).

"I regret to announce that I am withdrawing from the 2012 Australian Open. After several months of training and treatment, I am making steady progress to top competitive form," she posted on her website.

"My diet and fitness regimen have allowed me to make great strides in terms of my health and I am very close to being ready to return to WTA competition. I have every intention to return to the circuit in February."

Williams made the Australian Open final in 2003 before losing to her sister Serena. She reached the third round last year before retiring due to a hip injury in the opening set against Germany's Andrea Petkovic.